This invention relates to the technical field of stainless steel cut resistant, abrasion resistant and electrically conductive yarn, suitable for making fabrics and particularly knitting fabrics and garments, and to protective garments, such as cut resistant, abrasion resistant and/or electrically conductive gloves, aprons, smocks, jackets, trousers, leggings, socks or stockings, and the like, as well as protective fabric structures of all kinds, such as drapes and the like.
Cut resistance is important in a wide variety of industries, as lacerations are one of the greatest causes of industrial accidents. Notable are the meat cutting and butchering workers, machinists, carpenters and joiners, assembly line workers, and the like.
Abrasion resistance is comparably important in a variety of industrial contexts; also of significance is the incidence of abrasive exposure among athletes, particularly those performing on artificial turf and other harsh environments.
Electrical conductivity is a major asset in electronics industries, where grounding to dissipate static discharge is necessary to prevent damage to electronic components and assemblies.
A number of approaches have been followed to provide cut resistant, abrasion resistant and electrically conductive yarns, and for forming such yarns into fabrics and protective garments and the like.
Numerous attempts have been made to employ metallic yarns and wires. Wires are generally prohibitively difficult to work with, and are prone to breakage when worked and work hardened. Metallic wires are not particularly durable when exposed to abrasion, and numerous breaks occur during spinning, knitting, and in use.
High strength polymers have been substituted for metallic wires and yarns; among these are the aromatic polyamides, such as Kevlar.RTM., and ultra-high molecular weight polyolefins, such as Spectra.RTM. (Kevlar.RTM. is a registered trademarks of du Pont. Spectra.RTM. is a registered trademark of Allied Signal, Inc.) While these materials have met with some success, the level of cut resistance attained, and the bulk of fibers and yarns required, remain problems for users.
U.S. Pat. No. 3,883,898, Byrnes, teaches the employment of Kevlar.RTM. yarns in providing cut resistant garments.
More recently, composite metallic-polymer yarns have been employed. Such composites afford overall better properties, but the limitations of both metallic and synthetic polymers are still present to some degree.
U.S. Pat. No. 4,004,295, Byrnes, teaches a composite yarn of metallic wire and a Kevlar.RTM. yarn in providing cut resistant garments.
U.S. Pat. No. 4,384,449, Byrnes, et al., teaches a composite yarn having a core of one or more strands of metal wire, served with two plies of Kevlar.RTM. fiber wrapped in opposite directions.
U.S. Pat. No. 4,470,251, Betticher, teaches a composite yarn having a core of one or more strands of metal wire, served with two plies, the first of Kevlar.RTM. fiber wrapped in one direction, the second of Nylon.RTM. polyamide wrapped in the opposite direction.
U.S. Pat. No. 4,777,789, Kolmes, et al., teach a composite having a polymer core, of a variety of natural and synthetic fibers, a wrapping of wire, and a serving over the wire wrapping of two counter wound plies of non-metallic fibers. U.S. Pat. No. 4,838,107 is a Continuation, having the same disclosure.
U.S. Pat. No. 4,912,781 is a composite yarn with a polymer fiber core having a metallic wire knit over the core; the composite thus formed may be served, braided or over-knit with a synthetic polymer fiber outer cover.
Wire and wire cored metallic yarns are quite difficult to knit or otherwise fabricate into protective garments.
The garments are generally bulky, stiff and heavy. In the form of gloves, limited flexibility and tactility constrain the functionality of the gloves.
Efforts to reduce the diameter of metallic wire cores in multiple strands result in the development of excessive torque and liveliness which limits the ability to knit gloves or other protective garments. In workable yarns with limited metallic content, cut resistance is often inadequate.
Wire cored yarns are prone to breakage when knit, flexed, bent, or otherwise manipulated, compromising the protective value and properties for which it is employed.